Electrode boiler



Nov. 15, 1955 E. B. BATES 2,724,045

ELECTRODE BOILER Inventor EMILE BERNARD ATES Nov. l5, 1955 E. B. BATES 2,724,045

ELECTRODE BOILER Filed Aug. l5, 1952 3 Sheets-Shfel'I 2 Inventor EMILE BERNARD BATES Nov. 15, 1955 E. B. BATES 2,724,045

ELECTRODE BOILER Filed Aug. l5, 1952 3 Sheets-Sheet 5 Uni rates Patent 2,724,045 ELECTRDE EOILER Emile Bernard Bates, Leicester, England Application August ,15, 1952, Serial No. 304,556 7 Ciaims. (Cl. 2ML-4t?) This invention concerns electrode boilers, that is to say, boilers in which a liquid is heated by the passage of an electric heating current through it between electrodes at least partially immersed in it. An object of the invention is a boiler (and especially a boiler for raising steam) which is inexpensive to produce and is economical in its current consumption and which is self-regulating. Existing electrode boilers for raising steam require various control devices in order to ensure their safe operation. Among these may be mentioned a water level control which controls, through a relay, a motor-driven pump so as to replenish the water in the boiler as evaporation takes place; a pressure control by which, if the pressure in the boiler exceeds a pre-determined amount, resistances are brought in to decrease the current consumption; a safety control which opens a valve in the boiler to reduce the water level should the current consumption exceed a pre-determined amount. A further object of the inven- .tion is a boiler which dispenses with these controls.

This invention provides an electrode boiler comprising a closed gravity fed tank, a plurality of electrodes extending part way along the height of the tank so as to be at least partly immersed in the water and to pass a heating current through the latter, a steam outlet from an upper part of the tank, and a feed water inlet to a lower part of the tank. Since the tank is gravity fed it will be appreciated that the pressure under which the steam is generated is determined by the head of the feed.v As the volume of steam builds up in the boiler the water level in the latter will be lowered, water being expelled back up the feed pipe. Therefore the extent to which electrodes are immersed will decrease, with a consequent decrease in current consumption and in heat supplied and steam generated. Thus an automatic control of current consumption and steam generation is obtained.

According to an important subsidiary feature of the invention the capacity of that part of the tank which lies L between the steam outlet and the lower end of the effective length of the electrodes is not greater than, and is preferably less than, the capacity of that part which lies .between the inlet and the lower end of theeffective length of the electrodes. This feature obviates the danger that boiling water may pass back to the gravity feed tank or its equivalent. Considering as an example a preferred construction in which the said parts of the tank are of uniform cross sectional area and the electrodes extend for not more'than half the distance between the steam outlet and the water inlet, the electrodes may heat a column of water of a height equal to their length. As steam generation continues this column of water is forced downwards. lf its volume is greater than the volume of the tank between the effective lower ends of the electrodes and the water inlet a part of the boiling water will pass back along the feed pipe and will eventually reach the supply tank. The boiling waterwill be replaced by cold water owing in the opposite direction and a pulsating flow will be set up which eventually results in the sudden ejection of a large volume of boiling water into the feed tank. On the other hand if the volume of the lower part of the tank .is greater than that of the .column of water, the water level sinks below the effective lower ends of the electrodes (so. that currentflow and vca n enter the feed pipe.

ICC

The invention further includes electrode boiler apparatus comprising a closed boiler tank, a header or supply tank at a higher location, a gravity feed connection leading from the header to the water inlet at a lower part of the boiler tank, a steam outlet from an upper part of the boiler tank, and electrodes extending part way along the height of the boiler tank with the lower ends of their effective lengths at a level below the steam outlet but above the water inlet so as to be at least partly immersed in and to pass current through the water, the

Varrangement and construction being such that the steam is generated under a pressure determined by the head of water in the header without the passage of boiling water into the latter.

The invention further includes a method of generating isteam which consists in passing electric current between electrodes through water contained in a closed boiler and gravity fed from a header under conditions such that the steam pressure is governed by the head of water in the header, the water level in the boiler and the extent to which thetelectrodes are immersed being governed by the steam volume in the boiler, and the positioning of the electrodes being such that boiling water cannot pass over the header. v The foregoing and other provisions in accordance with theinvention will be more clearly understood by reference to the following description of the construction and operation of a preferred form of electrode boiler which is illustrated in the accompanying drawings.

In the drawings:

Figure lA is a front View of the electrode boiler and Figure 1B is a front view of the header connected thereto;

Figure 2 is a side view of the boiler;

Figure 3 is a diagrammatical plan view showing the relative position of the electrodes, and

Figure 4 is an electrical circuit diagram showing the circuit of the boiler and associated parts.

Referring to Figures lA, 1B and 2 the boiler comprises a cylindrical tank 10 of uniform diameter disposed with its axis vertical and mounted on a supporting base 11. `A feed pipe 12 leads into it at or near .its bottom from a supply tank or header 13 which is dis- :posed at a higher level and is kept lled with water at a pre-determined constant level by a ball valve 14 orA its equivalent. The feed, pipe 12 is connected by a pipe 15 (which may have a shut off valve 45) to the supply tank 1,3. The supporting base 11 has mounted forwardly on it in front of .the tank 10 a panel 16 on which are mounted an electrical switch face 1'7, an ammeter 18, indicator lamps 19 and lamp fuses 20.

A steam outlet pipe 2l, provided with a suitable shut-olf valve Z2, extends from the top part of the tank and three electrodes depend vertically from near the top Vof `the tank to a level somewhat above the mid-position between the -waier inlet and the steam outlet. These electrodes 23 are arranged to be connected to the respective phases of insulating sleeve 2e' serving to space the exposed part of the electrode from its fixing plate. rfhe steam outlet pipe 21 is provided with a dead weight safety valve 27 and with a pressure gauge 2S and control valve 29. At the side of the boiler 2 is a sight glass 30, forming part of a tube 31 which has upper and lower connections 32 and 33 with the interior of the boiler. Valves 34 and 35 may be .provided to bring the sight glass into and out of operation. A

drainage cock 36 may be provided at the bottom of the tube 31.

The electrical connections are shown diagrammatically in Figure 4 in which are shown leads 37 extending from a three-phase alternating current supply and connected to the lower terminals of the switch fuse 17 the outgoing terminals of the latter being connected by wires 38, 39 and 4G to the electrodes 23. The ammeter 18 is connected in circuit with the lead 4i). The indicator lamps 19 and their fuses 20 are connected respectively by leads 41, 42, 43 to the leads 38, 39 and 49, each fuse being connected in series with one terminal of the lamp the other terminals of the lamps being connected together by a common conductor 44.

It will be appreciated that the passage of current between the electrodes 23 heats the water and a volume of water in the upper part of the tank lil is brought to boiling point, thereby generating steam. The steam occupies a space at the top of the boiler above the water and it is therefore generated under a pressure which is controlled by the head under which the boiler is supplied, that is to say, by the difference in water level between that in the boiler 10 and that in the supply tank 13. If the steam is not drawn olf or is generated faster than it is drawn off, the water level in the boiler 16 will be forced down so that the electrodes 23 are immersed to a less extent. This is automatically accompanied by a drop in current ow between the electrodes 23. Thus, not only is the current consumption automatically adjusted, but the decrease in current ow causes a decrease in steam generation, with the result that the steam generation in the boiler tends to reach a state of equilibrium.

In certain instances where the natural salt content of the water is relatively high (that is a high concentration of lime salts appertains) there may be a tendency for salts to become deposited on the surfaces of the insulating supporting bushes in which the electrodes are mounted, which tendency, if excessive, may cause a ash over or direct short circuit either to earth or across the electrodes. It is to lessen the risk of such a flash over or short circuit that the insulating sleeves 26 are provided, these serving to increase the lengths of the leakage paths. When dealing with Waters of high degrees of hardness it may be found desirable to counteract this tendency still further by adopting an alternative form of construction wherein the electrodes are supported on insulating rods or sleeves extending up from the bottom of the enclosed tank or boiler (and containing the electrical leads), such insulating rods or sleeves serving to determine the lower ends of the elective lengths of the electrodes. With the electrodes supported from below as just described, the insulating bushes and sleeves (or at least the major portions of the latter) are always immersed. Crystalline salts cannot then form and so any ash over is precluded.

I claim:

l. An electrode boiler comprising a vertical boiling chamber, an electrode support at the top of said chamber, bolts depending from said support, electrodes suspended on the lower ends of said bolts, and insulating sleeves on said bolts extending from the electrodes to the support, the lower ends of the electrodes being not more than half way down the boiling chamber, a header tank for supplying cold water, a feed pipe from said tank to the bottom of the boiler, a steam draw-off at the top of the boiler above the electrode support, and a safety valve at the top of the boiling chamber.

2. In an electrode boiler the combination comprising a vertical boiling chamber, insulating supporting means for electrodes at the top of said chamber, heating electrodes depending from said supporting means, a stream draw-off outlet at the upper part of said chamber, a valve controlling said outlet and a cold water supply inlet opening into the bottom of said chamber, the heightwise distance from said inlet to the bottoms of said electrodes being at least equal to the length of said electrodes.

3. In an electrode boiler the combination comprising a vertical boiling chamber, insulating means for heating electrodes at the top of said chamber, heating electrodes depending from said supporting means and contained entirely within the upper half of the chamber, a steam drawot outlet at the upper part of said chamber, a valve controlling said outlet, a safety valve at the top of the boiling chamber and a cold water supply inlet opening into the bottom of the lower half of said chamber.

4. An electrode boiler comprising a vertical boiling chamber, an electrode support at the top of the said chamber, electrodes suspended from said support to depend downwardly therefrom, stems at the upper ends of said electrodes for anchoring them to said supporting means, insulators interposed between said stems and said supporting means, clamping means for securing the stems of the electrodes to the supporting means, a header tank for supplying cold water, a feed-pipe from said tank to the bottom of the boiler, a steam draw-off at the top of the boiler above the electrodes, and a valve controlling the steam draw-olf the lengths of the electrodes being such as to cause them to extend not more than half way down the boiling chamber.

5. An electrode boiler comprising a vertical boiling chamber, an electrode support at the top of said chamber, stems mounted in said electrode support, insulating means interposed between said stems and the support, electrodes carried by said stems to depend from the support with the lower ends of the electrodes not more than half way down the boiling chamber, a header tank for supplying cold water, a cold water inlet opening into the bottom of the boiling chamber, a steam draw-off at the top of the boiling chamber above the electrodes, a valve controlling said steam draw-ofi and a feed pipe from said tank to said inlet, the positioning or" said inlet being such that its heightwise distance from the lower ends of the electrodes is not less than the length of the electrodes.

6` ln an electrode boiler, the combination comprising a vertical cylindrical boiling chamber, a plurality of rodlike electrodes depending from the top of said chamber and spaced equally around the axis thereof, supporting means for mounting the upper ends of said electrodes, insulators interposed between the said electrodes and the said mounting means, a steam draw-olf outlet at the upper part of said chamber above the electrodes, a valve controlling said outlet and a cold water supply inlet opening into the bottom of said chamber and spaced height-wise below the lower ends of said electrodes by at least the length of the electrodes.

7. In an electrode boiler the combination comprising a vertical cylindrical boiling chamber, heating electrodes depending from the top of the said chamber and spaced equally around the axis thereof, supporting means for the electrodes at the top of said chamber, insulators interposed between the electrodes and said supporting means, a steam draw-olf outlet at the upper part of said chamber, a valve controlling said outlet, a sight glass level indicator associated with the boiling chamber, connections from said indicator to the top and the bottom of the boiling charner, a cold water supply inlet at the bottom of the said chamber, the length of the electrodes and the position of the said inlet being such that the inlet is displaced heightwise below the lower ends of the electrodes to an extent at least equal to the length of the electrodes.

References Cited in the le of this patent UNITED STATES PATENTS 1,352,547 Seimbille Sept. 14, 1920 1,502,294 De Kermor July 22, 1924 1,527,761 Unland Feb. 24, 1925 1,571,165 Fuss Jan. 26, 1926 1,738,733 Schur et al Dec. 10, 1929 2,538,648 Livingstone Jan. 16, 1951 2,627,015 Hackman Jan. 27, 1953 

